Motion responsive rocket firing system



July 23, 1963 G. H. FRY, JR

MOTION RESPONSIVE ROCKET FIRING SYSTEM 2 Sheets-Sheet 1 Filed Aug. 9, 1961 INVENTOR GEORGE H. FRKJR.

@ECA BY ai Z ATTORNEYS July 23, 1963 G. H. FRY, .JR 3,098,411

MOTION RESPONSIVE ROCKET FIRING SYSTEM QN BY ATTORNEYS United States Patent C 3,098,411 MGTION RESPQNSIVE ROCKET FIRING SYSTEM George H. Fry, Jr., Pittslield, Mass., assigner, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed Aug. 9, 1961, Ser. No. 130,428 1s Claims. (ci. 89-41) The present invention relates to -a system for predicting the position of an oscillating platform, and more particularly, to a system for predicting the position of the deck of a ship during the tiring of a missile.

The firing of missiles from the deck of a ship while under way ygives rise to the possibility of collision between the deck of the ship and the missile during the l'irst few seconds of take-olf. This problem is particularly prevalent when the missile firing is attempted during heavy seas. Since a prescribed period of time lapses between the initiation of tiring and the actual build-up of thrust a collision preventative system must predict the position of a ship during this period of tim-e.

The instant invention is based upon the expectations that with a steady course and speed a ships motion during the launching period will be approximately sinusoidal and of uniform frequency and magnitude. This invention operates in response to a deck mounted accelerometer to prevent launching of a missile when there is a possibility of collision of the missile and the deck of the ship during a prescribed time interval subsequent to the initiation of tiring.

An object of the present invention is to avoid firing of a missile when there is a possibility of missile and deck collision.

Another object is to provide a system to predict the position of the deck of a ship during a prescribed time interval.

A further object of the invention is to prevent missile launching by predicting in advance the position of a ships deck during the time interval between the initiation of firing and the Ibuild-up of missile thrust.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following description when `considered in connection with the accompanying drawings wherein:

FIG. 1 illustrates a diagram of a rst embodiment of the invention.

FIG. 2 illustrates a diagram of a `second embodiment of the invention.

Referring now to the drawings wherein like reference characters designate like corresponding parts throughout several views, there is shown in FIG. l an input l of a sinusoidal wave such as 11 from a -deck mounted accelerorneter (not shown). The input is fed to a rectier 12, filter 13 and an amplifier 14 having an adjustable sensitivity to determine whether the deck motions are o-f suflicient amplitude to make use of the deck motion predictor necessary. If the sinusoidal wave representing the peaks of the deck motions is below a given amplitude the relay l15 will main-tain contact 15 in its normally open position. Thus, since contact 15" of relay 15 will remain in its normally closed position, no power will be delivered to the deck motion predictor. Under these conditions, ring of a missile may be initiated from a tiring key at through closed contact 15 of relay 15 to the tiring circuit input 21.

lf the peaks of the sinusoidal wave representing the deck motions are greater than a given amplitude, relay .15 will be energized thereby opening contact 15 and closing contact 15". Thus power from input 22 will be delivered to the deck motion predictor through contact 15" of relay 15. Under these conditions, the firing circuit from the ICE firing key at 20 to the tiring circuit input at 21 can be energized only when a deck Imotion predictor contact 16' of relay 16 is closed. In the operation of the deck motion predictor the input sinusoidal wave 11 is `fed to an amplifier and clipper `2.3y whose output is a symmetrical square wave 24 having -a frequency the same as the input frequency. The phase comparator 25, low pass filter 26, integrator 27, and servo ampliiier 23 function to control the speed at which motor 30 will operate to drive the cam 31 and ultimately the cam switch 32. The configuration of the cam 31 is such that the cam switch 3-2 is open 50 percent of the time and closed 50 percent of 4the time. The speed of the motor and therefore the rotation of the cam is controlled so that the on-olE action of the cam switch 312 approximates the -square wave 24 which represents the -ships sinusoidal motions. Thus the on-oi action of the cam switch 32 in response to the camr31 yforms the square wave 3,3 lfrom the Voltage applied to the cam switch 32 through the input terminal 29. The output of the cam switch 32, a square Wave 33, is fed through a three second delay 34 back to the phase comparator 25.

Initially the nominal speed of the motor 3G is set manually .by adjusting the nominal speed bias of the servo amplilier -28 so that the motor speed corresponds to the known natural frequency of the ships motion. The low pass filter 26, integrator 27, and servo ampliier 2-8, in response to the output of the comparator, control the motor speed so that the predictor output Ifrom cam switch 32 which is Ifed through the three second delay 34 is in phase at the phase comparator 25 with the square Wave 24 which represents -the sinusoidal wave 11 and the actual motion of the ships deck. Thus, the output of cam switch 32 is, prior to the three second delay 34, three seconds in advance of the actual motion of the ships deck. This output of cam switch 32 is fed to relay 16, Thus, relay 16 senses the output from the cam switch 32 in such a manner that the relay l16 is energized to open and close relay contact 16'. When relay contact 16 is closed the circuit from the input firing key at 20 through to the input to the tiring circuit 21 is complete and ring may be initiated.

This means that the predictor output as sensed by relay 16 is approximately identical to the ships motion input except that it is three seconds ahead of the ships motion input. Therefore, relay 16 is capable of anticipating the occurrence of detrimental positive deck accelerations by a time period of three seconds, and through its contact 16 prevents the energizing of the iiring circuits during this period.

While the delay 34 has been described as being set for a period of three seconds the appropriate time value of a delay may Vary in accordance with the time required to build up thrust in a particular missile. Thus, if because of a slow 'build-up time yof thrust in a particular missile there is possibility of deck and missile collision for a period in excess of or less than three seconds, the delay 34 would appropriately be adjusted `to that particular time period.

The embodiment of the invention as set forth in FIG. 2 operates in a similar manner to that as set forth in FIG. l. However, the use of a tape recorder 42 is substituted for that of a cam and cam switch as in FIG. 1. The square wave output 201- frorn the amplifier and clipper 23 is fed to both a modulator 46 and a comparator 59. In lche modulator, the square wave pulses a high frequency source and the output then consists of `a group of high frequency oscillations 41 and these are recorded on a recording drum or la continuous tape. Recording head 43 records in the recording drum 44 being rotated by a synchronous motor 45. As the drum 44 is being driven at a constant speed by the ysynchronous motor 4S the signals recorded by recording head 43 are read one cycle later in time by a positionable reading head 46. The modulated signal received by reading head 46 is demodulated and amplified by 47 into a square wave which is compared by the comparator 50 with the incoming Square wave 24. The output `of the comparatori 50 1s amplified by amplifier 51 and fed to a motor 52 which adjusts the position of the reading head until the demodulated recorder output is in phase with the amplified and clipped input 24. The motor With its positioning signal received from comparator 50 has its polarity dependent upon the time relationship between the input and recorded signals. Attached to the adjustable reading head 46 and also adjustable is another reading head 53 which is displaced three seconds earlier alon-g the circumference of the constant speed drum 44. This reading head 53 picks up exactly the same signal picked up by reading head 46, that is, compared with and maintained in phase with the input signal 24 except that the signal read by reading head 53 is three seconds in advance of that received by reading head 46. The signal received by reading head 53 is demodulated and amplified at 54 and fed to relay 16. ln sensing the output from recording head 53 relay 16 is capable of anticipating the occurrence of detrimental positive deck accelerations by a time period of three seconds and through its contact 16 prevents energiZat-ion of the firing circuits during this period. Relay 16, therefore, `opens and closes the circuit between the input firing key at 20 and the input to the firing circuits at 2,1 in accordance with the predicted position of the ships deck :for a prescribed time period after initiation of firing.

As in FIG. 1, where the build-up time of thrust for a particular missile is in excess or less than three seconds, the position of reading head 53 may be varied in relationship to the recording head 46 to avoid the possibility of collision between the time of initiating firing and the time of build-up of missile thrust. That is, the reading head 53 may be adjusted relative to reading head 46 in accordance with a predetermined thrust build-up time and thereafter by interconnected relationship with the reading head 46 be adjustably positioned by motor 52.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the linvention may be practiced otherwise as specifically described.

What is claimed and desired to be secured by Letters Patent of the United States is:

l. In a device for predicting the future position of a moving object the combination comprising;

an input signal indicative of the instantaneous position of a iirst moving object;

a first relay responsive to `a prescribed amplitude from said input signal, said first relay comprising a first contact adapted for connection into and control of a fire control circuit and `a second contact in a power supply whereby in response to the signal of prescribed amplitude said first relay opens said first contact and closes said second contact;

a motion predictor;

a drive means operably connected to said signal, said drive means being controlled by said signal when said first relay closes said second contact to connect the power supply to the drive means and thereby actuate said motion predictor;

said motion prediction means being controlled by said drive means for producing a signal indicative of a future position of said first moving object relative to a second object; and

a second relay connected to said prediction means to close an associated fire control circuit when the future positions of said first and second moving objects are in non-collision positions relative to each other.

2. A motion predictor as claimed in claim 1 wherein said means for controlling said drive means comprises a phase comparator, -a low pass filter, and an integrator, said integrator being operable to control the speed of said drive means.

3. A motion predictor as claimed in claim 2 wherein said prediction means controlled by said drive means comprises a cam and a cam switch.

4. A motion predictor as claimed in claim 1 wherein said drive means is a motor, said motor being operable to position said prediction means controlled by said drive means.

5. A motion predictor 'as claimed in claim 4 wherein said motion predicting means controlled by said drive means is at least one recorder reading head.

6. A :mot-ion predictor comprising drive means; switch mean-s driven by said drive means; delay means connected to said switch means for delaying the output thereof for a prescribed time period; an input indicative of oscillatory movement of an object; an amplifier and clipper responsive to said input for converting said input into a square wave; a power supply; a relay responsive to a prescribed amplitude of said input and comprising a first contact in a fire control circuit and a second contact in the power supply wherein in response to the prescribed amplitude of said input said relay opens said first contact and closes said second contact; and a speed con trol means connected to said power supply and delay means yand said amplifier and clipper for controlling said drive means whereby said switch means produces pulses which, after being delayed by said delay means, match said input in frequency and phase.

7. A motion predictor as claimed in claim 6 wherein said switch means comprises a motor driven cam and a cam switch.

8. A mot-ion predictor as claimed in claim 7 wherein said speed control means comprises a phase comparator connected .to the outputs of said amplifier and clipper, and said delay means whereby said outputs are compared; a low pass filter connected to the output of said comparator for :adjusting the phase o-f said comparator output; an integrator connected to the output of said comparator for adjusting speed of said drive means; and a servo amplifier connected to said power supply, and to the outputs of said low pass filter and said integrator for amplifying said outputs whereby said motor is driven at the speed necessary for said cam operated switch to produce pulses which, after being delayed by said delay means, match said input signal in frequency and phase.

9. A motion predictor comprising an input indicative of oscillatory movement of an object; an amplifier and a clipper responsive to said input for converting said input into 4a square Wave; a modulator connected to said ampllfier and clipper output; a recorder connected to the output of said modulator; ia rst dernodulator and amplifier; a first recorder output connected to said first demodulator and amplifier; a comparator connected to the output of said amplifier and clipper, and said first demodulator and amplifier to compare said outputs; correcting means for `adjusting said first recorder output to match said amplifier :and clipper output; a second demfodulator and amplifier; a second recorder output connected to said demodulator and amplifier; a first relay responsive to a prescribed amplitude of said input to conneet a power supply to said second dem-odulator and ampller; and a second relay connected to the output of said second demodulator and amplifier wherein said second recorder output is read earlier in time than said first recorder output thereby being indicative of future motion of said object.

10. A motion predictor comprising an input indicative of oscillatory movement of an object; an amplifier and a clipper responsive to said input for converting said input into a square Wave; a modulator connected to said amplifier .and clipper; a recorder comprising -a recording drum, a synchronous motor for rotating said recording drum at a constant speed, a recording head connected to the Aoutput of said modulator for recording on said drum, a first adjustable reading head and a second adjustable reading head adjustably interconnected, said second adjustable reading head being positioned to receive the signal recorded by said recording head a prescribed period of time earlier tha-n said first reading head; a first demodulator and amplifier connected to the output of said first reading lie-ad; a comparator connected to the outputs of said amplifier and clipper, and said first demodulator and amplifier to compare the outputs thereof; an amplifier connected to said comparator to amplify the output of said comparator; a motor connected to said amplifier and said interconnected reading heads and responsive to the amplified output of the comparator whereby said motor adjusts the position of said first reading head so that said compared outputs 4are matched; a second demodulator and amplifier being connected to the output of said second reading head; a first relay responsive to a prescribed amplitude of said input to connect a power supply to said second demodulator and amplifier; and a second relay connected .to the -output of said second demodulator and amplifier whereby said second relay senses pulses indicative of a future position of said object, thereby predicting motion of said object.

l1. A fire control system comprising a power supply; an input indicative of oscillatory movement of a first object; a first relay responsive to a prescribed -amplitude of said input and comprising a first contact in a fire control circuit and a second contact in a power supply wherein in response to the prescribed amplitude of said input said first relay opens said first contact and closes said second contact; a motion predictor for predicting the future position of said first object in relation to a second object and connected to said power supply through said second Contact; and a second relay connected to the output of said motion predictor whereby said second relay closes said fire control circuit when the future positions of said first and second objects are non-:collision positions.

12. A fire control system as claimed in claim 11 wherein said motion predictor comprises drive means; switch means driven by said drive means; delay means connected to said switch means for delaying the output .thereof for a prescribed time period; an amplifier and clipper responsive to said input for converting said input into a square wave; speed control means connected to said power supply, said delay means, and said amplifier and clipper for controlling said drive means whereby said switch produces pulses which after being delayed by said delay means, match said input in frequency and phase.

13. A fire control system as claimed in claim 12 wherein said switch means comprises a motor driven cam and a cam switch.

14. A fire control system as claimed in claim 13 wherein said speed control means comprises a phase comparator connected to the outputs of said amplifier and clipper, and said delay means whereby said outputs are compared; a low pass filter connected to the output of said comparator for adjusting a phase of said comparator output; `an integrator' connected to the output of said comparator for adjusting the speed of said drive means; and a servo amplifier connected to said power supply and to the outputs of said low pass filter and said integrator .for amplifying said outputs whereby said motor is driven at the speed necessary `for said cam operated switch to produce pulses which, after 4being delayed by said delay means, -mateh .said input in frequency and phase.

15. A `fire control system as claimed in claim l1 wherein said motion predictor comprises an amplifier and -a clipper respon-sible to said input .for converting said input .into a square wave; a modulator connected to said amplifier and clipper output; a recorder connected to the output of said modulator; a first demodulator and amplifier; a first recorder output connected to said demodulator and amplifier; a comparator connected to said output of said amplifier and clipper and said first demodulator and amplifier to compare said outputs; correcting means responsive to said comparator output -for adjusting said first recorder output to match 4said amplifier and clipper output; a second demodulator and amplifier; a second recorder output connected to said second demodulator and amplifier; a power supply connected to said sec-ond demodulator and amplifier; and a relay connected to said second demodula-to-r `and amplifier wherein said second recorder output is read earlier in time than said first recorder output thereby being indicative of future motion of said object.

16. A fire control system as claimed in claim 15 wherein said recorder comprises a recording drum, a synchr-cnous motor for rotating said recording drum at a constant speed, a recording head connected .to the output of said modulator for recording on said drum, a first adjustable reading head and a second adjustable reading head adjustably interconnected, said second adjustable reading head being positioned to read the signal recorded `by said recording head a prescribed period of time earlier than said first reading head.

17 A fire ycontrol system as claimed in claim 16 wherein said rst recorder 4output and said second recorder output comprise respectively the outputs of said fir-st and second reading heads.

18. A fire control system -as claimed in claim 17 wherein said correcting means comprises an 4amplifier for `amplifying said comparator output, and a motor er1- ergized by said amplifier output wherein said motor ladjusts the position ot said interconnected reading heads thereby 4matching said amplifier and clipper, and said first demodulator and amplifier outputs.

References Cited in the file of this patent UNITED STATES PATENTS 2,088,654 Hull Aug. 3, 1937 

6. A MOTION PREDICTOR COMPRISING DRIVE MEANS; SWITCH MEANS DRIVEN BY SAID DRIVE MEANS; DELAY MEANS CONNECTED TO SAID SWITCH MEANS FOR DELAYING THE OUTPUT THEREOF FOR A PRESCRIBED TIME PERIOD; AN INPUT INDICATIVE OF OSCILLATORY MOVEMENT OF AN OBJECT; AN AMPLIFIER AND CLIPPER RESPONSIVE TO SAID INPUT FOR CONVERTING SAID INPUT INTO A SQUARE WAVE; A POWER SUPPLY; A RELAY RESPONSIVE TO A PRESCRIBED AMPLITUDE OF DAID INPUT AND COMPRISING A FIRST CONTACT IN A FIRE CONTROL CIRCUIT AND A SECOND CONTACT IN THE POWER SUPPLY WHEREIN IN RESPONSE TO THE PRESCRIBED AMPLITUDE OF SAID INPUT SAID RELAY OPENS SAID FIRST 